We report observations of transitions associated with biexcitons in ${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As/GaAs multiple–quantum-well structures of well widths from 200 to 350 Å, using resonant excitation and photoluminescence spectroscopies. The observed biexciton binding energies agree well with those calculated by Kleinman [Phys. Rev. B 28, 871 (1983)]. In contrast, earlier measurements by Miller et al. [Phys. Rev. B 25, 6545 (1982)] gave biexciton binding energies which agreed with Kleinman’s results for well sizes below 150 Å but were significantly greater for larger well sizes. In addition, we report on the biexciton emission-strength dependence on pump power, temperature, and applied-magnetic-field strength.

• Received 16 January 1989

DOI:https://doi.org/10.1103/PhysRevB.40.3340